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§1646. Tower Scaffolds and Rolling Scaffolds, Wood or Metal.

(a) The minimum dimension of the base of any free-standing tower or rolling scaffold shall not be less than 1/3 the height of the scaffold unless such scaffold is securely guyed or tied. For restrictions when worker rides scaffold see paragraph (f) following.

(b) Construction and Erection.

(1) The uprights, ledgers, ribbons, braces, and splices shall be equivalent to the standards specified in other applicable Sections of these Orders. Railings are required if the platform is 7 1/2 feet or more above grade. Railings shall be installed in accordance with the provisions of Section 1644(a)(6).

NOTE: Toeboards or side screens may also be required. (See Section 1621.)

(2) The screw jack shall extend into its leg tube at least 1/3 its length, but in no case shall the exposed thread exceed 12 inches.

(3) The uprights (legs of rolling scaffolds) shall not exceed 24 inches without being braced according to the manufacturer's specifications.

(c) Wheels or casters of rolling scaffolds shall be provided with an effective locking device, and kept locked when workers are climbing or working on the scaffold. At least 2 of the 4 casters or wheels shall be a swivel type. All wheels or casters shall be properly designed for strength and dimension to support at least 4 times the maximum intended load.

(d) Joints of metal scaffolds shall be locked together with lock pins, bolts or equivalent fastening, including caster joints. Lock pins used must be of a locking type.

EXCEPTION: Screw jacks and guardrail posts.

(e) Platform planks on rolling or tower scaffolds shall not project farther than 18 inches past supports at the edges of the scaffold. An effective method of preventing platform planks on rolling scaffolds from slipping off must be provided. The nailing of cleats of 1-inch material on the underside of each projecting end, or other equivalent means, will be acceptable. Platforms shall be tightly planked for the full width of the scaffold except for any necessary entrance openings.

NOTE: Refer to Orders 1621 and 1637(f) for regulations on required plank and platform sizes.

(f) Ladders. Ladders or other unstable objects shall not be placed on top of rolling scaffolds to gain greater height.

(g) Scaffolds on Vehicles. When scaffolds are built on motor trucks or vehicles, they must be rigidly attached to the truck or vehicle. The attachment must be made in a manner that will develop the full strength of the scaffold in resisting an overturning force.

(h) Trucks or vehicles that have scaffolds attached to them shall have a device in use whenever employees are on the scaffold that prevents swaying or listing of the platforms.

(i) Riding. Employees may ride on rolling scaffold moved by others below if the following conditions exist:

(1) The floor or surface is within 3 degrees of level, and free from pits, holes, or obstructions;

(2) The minimum dimension of the scaffold base, when ready for rolling, is at least 1/2 of the height. Outriggers, if used, shall be installed on both sides of staging;

(3) The wheels are equipped with rubber or similar resilient tires. For towers 50 feet or over, metal wheels may be used;

(4) The manual force used to move the scaffold shall be applied as close to the base as practicable, but not more than 5 feet (1.5 meters) above the supporting surface of the scaffold;

(5) Before a scaffold is moved, each employee on the scaffold shall be made aware of the move; and,

(6) No employee shall be on any part of the scaffold which extends outward beyond the wheels, casters, or other supports.

(j) Riding on a Self-Propelled Scaffold. One employee may ride on and move a rolling scaffold while on the platform without assistance from others below provided the following conditions are met:

(1) All of the provisions in subsection (i) of this Section shall be met, except that the scaffold need not be moved by others below;

(2) The scaffold platform shall not be more than 4 feet above the floor level;

(3) The working platform shall be no less than 20 inches in width with a maximum 1 inch space between platform planks;

(4) Wheels or casters of rolling scaffolds shall be provided with an effective locking device that is used in accordance with subsection (c) of this section; or rolling scaffolds shall be provided with an effective device that is used to prevent movement of the scaffold when workers are climbing or working on the scaffold; and,

(5) The use of power systems such as motor vehicles, add-on motors, or battery powered equipment to propel a rolling scaffold is prohibited.

(k) Training. Employees who ride on rolling scaffolds and employees that assist in moving employees riding on a rolling scaffold shall be trained in accordance with the requirements of this Section and with the requirements of the Construction Safety Orders, Section 1509 to recognize the hazards associated with riding on a rolling scaffold.